Material Editor > Type button > Material/Map Browser > Set Compatible With to Renderer (if necessary) > Top/Bottom
The Top/Bottom material lets you assign two different materials to the top and bottom portions of an object. You can blend the materials into one another.
The object's top faces are those whose normals point up. The bottom faces have normals that point down. You can choose whether "up" and "down" refer to the scene's world coordinates or to the object's local coordinates.
Note: If even one sub-material has its shading set to Wire (see Shader Basic Parameters Rollout), the entire material displays and renders as a wire material.
To create a top/bottom material:
In the Material/Map Browser, choose Top/Bottom and then click OK.
A Replace Map dialog is displayed. This dialog asks whether you want to discard the original material in the slot, or retain it as a sub-material.
The Top/Bottom material controls let you choose the two materials, and also the transition between them.

Top Material and Bottom Material—Click to display the parameters for the top or bottom sub-material. By default, a sub-material is a Standard material with Blinn shading.
The check box to the right of each button lets you turn off that material, making it invisible in the scene and in the sample slot.
Swap—Swaps the position of the top and bottom materials
Controls in this group let you choose how the software determines the boundary between top and bottom.
World—Faces point up or down according to the scene's world coordinates. When you rotate the object, the boundary between top and bottom faces remains in place.
Local—Faces point up or down according to the object's local coordinates. When you rotate the object, the material rotates with it.
Blend—Blends the edge between the top and bottom sub-materials. This is a percentage that can range from 0 to 100. At 0, there is a sharp line between the top and bottom sub-materials. At 100, the top and bottom sub-materials tint each other. Default=0.
Position—Determines where the division between the two materials lies on an object. This is a percentage that can range from 0 to 100. 0 is at the bottom of the object, and displays only the top material. 100 is at the top of the object, and displays only the bottom material. Default=50.